Goldman Sachs and four other financial firms are facing claims that they rigged the $550 billion market for bonds backed by Fannie Mae and Freddie Mac, according to Bloomberg.

In the Southern District of New York, a proposed class action suit accuses the institutions of driving down the offer that they bought unsecured bonds at and “pumping” up the bid at which they sold them over the counter.

The judge concluded that traders from these banks engaged in price fixing by using industry chatrooms, which exist primarily so that banks, dealers and co-underwriters can work together on a limited basis to find opening prices for bond issuances. However, in this case, four chat logs instead offered evidence that the traders discussed how to avoid a “race to the bottom” on the secondary market.

“This, on its face, is blatant price fixing,” he continued, dismissing the bank’s argument that those “authorized to coordinate on an opening price are allowed to have unrestricted pricing discussions during the syndication phase.”

The judge continued:

“If it is illegal to fix the secondary prices for bonds once they are on the market, it cannot be legal to fix such prices through conversations that occur right before.”

The judge also rejected the idea that four isolated chats weren’t sufficient enough to make up a conspiracy. Instead, the judge said that the tone of these four chats indicated that there were “many others”.